<template>

  <div class="app-container">

    <h2 style="text-align: center;">发布新课程</h2>

    <el-steps :active="1" process-status="wait" align-center style="margin-bottom: 40px;">
      <el-step title="填写课程基本信息"/>
      <el-step title="创建课程大纲"/>
      <el-step title="发布课程"/>
    </el-steps>

    <el-form label-width="120px">

        <el-form-item label="课程标题">
            <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写"/>
        </el-form-item>

        <!-- 所属分类：级联下拉列表 -->
        <!-- 一级分类 -->
        <el-form-item label="课程分类">
            <el-select @change="subjectLevelOneChanged"
                v-model="courseInfo.subjectParentId"
                placeholder="一级分类">
                <el-option
                v-for="subject in subjectNestedList"
                :key="subject.id"
                :label="subject.title"
                :value="subject.id"/>
            </el-select>
            <!-- 二级分类 -->
            <el-select v-model="courseInfo.subjectId" placeholder="二级分类">
            <el-option
                v-for="subject in subSubjectList"
                :key="subject.value"
                :label="subject.title"
                :value="subject.id"/>
            </el-select>
        </el-form-item>

        <!-- 课程讲师 -->
        <el-form-item label="课程讲师">
        <el-select
            v-model="courseInfo.teacherId"
            placeholder="请选择">
            <el-option
            v-for="teacher in teacherList"
            :key="teacher.id"
            :label="teacher.name"
            :value="teacher.id"/>
        </el-select>
        </el-form-item>

        <el-form-item label="总课时">
            <el-input-number :min="0" v-model="courseInfo.lessonNum" controls-position="right" placeholder="请填写课程的总课时数"/>
        </el-form-item>

        <!-- 课程简介-->
        <el-form-item label="课程简介">
            <tinymce :height="300" v-model="courseInfo.description"/>
        </el-form-item>

        <!-- 课程封面-->
        <el-form-item label="课程封面">

            <el-upload
                :show-file-list="false"
                :on-success="handleAvatarSuccess"
                :before-upload="beforeAvatarUpload"
                :action="BASE_API+'/oss/file/upload'"
                class="avatar-uploader">
                <img :src="courseInfo.cover">
            </el-upload>

        </el-form-item>

        <el-form-item label="课程价格">
            <el-input-number :min="0" v-model="courseInfo.price" controls-position="right" placeholder="免费课程请设置为0元"/> 元
        </el-form-item>

        <el-form-item>
            <el-button :disabled="saveBtnDisabled" type="primary" @click="saveOrUpdate">保存并下一步</el-button>
        </el-form-item>
    </el-form>
  </div>
</template>
<script>
import course from '@/api/edu/course'
import Tinymce from '@/components/Tinymce'

export default {
    //声明模块
    components: { Tinymce },
  data() {
    return {
      saveBtnDisabled: false, // 保存按钮是否禁用
      courseInfo: {
            title: '',
            subjectId: '',
            subjectParentId: '',
            teacherId: '',
            lessonNum: 0,
            description: '',
            cover: '/static/01.jpg',
            price: 0
      },
      courseId: '',
      teacherList: [],//讲师列表
      subjectNestedList: [],//一级分类列表
      subSubjectList: [],//二级分类列表
      BASE_API: process.env.BASE_API // 接口API地址
    }
  },

  created() {
    this.getTeacherList()
    this.getOneSubject()//得到一级分类
    if(this.$route.params && this.$route.params.id){//修改
        this.courseId = this.$route.params.id
        this.getCourseInfo()
    }
       
  },

  methods: {
    //得到课程基本信息
    getCourseInfo(){
        course.getCourseInfo(this.courseId).then(res => {
            this.courseInfo = res.data.courseInfo
            //由于添加只会得到一级分类，我们数据回显还需要二级分类也显示
            course.getAllSubject().then(res=>{
                this.subjectNestedList = res.data.items
                for(let i=0;i<this.subjectNestedList.length;i++){
                    let oneSubject = this.subjectNestedList[i]
                    if(oneSubject.id == this.courseInfo.subjectParentId){
                        this.subSubjectList = oneSubject.children
                    }
                }
            })
            
        })
    },
    //封面上传之前
    beforeAvatarUpload(file){
        const isJPG = file.type === 'image/jpeg'
        const isLt2M = file.size / 1024 / 1024 < 2

        if (!isJPG) {
            this.$message.error('上传头像图片只能是 JPG 格式!')
        }
        if (!isLt2M) {
            this.$message.error('上传头像图片大小不能超过 2MB!')
        }
        return isJPG && isLt2M
    },
    //上传成功之后
    handleAvatarSuccess(res,file){
        this.courseInfo.cover = res.data.avatar
    },
    //保存
    save(){
            course.saveCourseInfo(this.courseInfo).then(res=>{
            this.$message.success("课程基本信息添加成功")
            this.$router.push({ path: '/edu/course/chapter/'+res.data.courseId })
        })
    },
    //更新
    update(){
        course.update(this.courseInfo).then(res=>{
            this.$message.success("课程基本信息修改成功")
            this.$router.push({ path: '/edu/course/chapter/'+this.courseId })
        })
    },
    saveOrUpdate() {
        //判断是添加还是修改
        if(!this.courseInfo.id){
            //添加
            this.save()
        }else{
            this.update()
        }
    },
    getTeacherList(){
        course.getTeacherList().then(res=>{
            this.teacherList = res.data.items
        })
    },
    getOneSubject(){
        course.getAllSubject().then(res=>{
            this.subjectNestedList = res.data.items
        })
    },
    //当一级分类发生变化，此方法就会触发
    subjectLevelOneChanged(value){
        //将二级分类先清空
        this.courseInfo.subjectId = ''
        //这里的value模板自动封装了，就是id
        for(let i=0;i<this.subjectNestedList.length;i++){
            let subject = this.subjectNestedList[i];
            if(subject.id === value){//将这个一级分类封装的二级分类赋值给二级列表
                this.subSubjectList = subject.children
            }
        }
    }
  }
}
</script>
<style scoped>
.tinymce-container {
  line-height: 29px;
}
</style>